Method and apparatus for inductively heating valve seats

ABSTRACT

A method and apparatus for simultaneously heating the conical surfaces of first and second valve seats lying generally in a given plane on an engine component, which method and apparatus comprises mounting two inductors for independent reciprocal and lateral movement with respect to a common frame and biased outwardly therefrom, moving the common frame toward the plane of the valve seats until each is stopped by contacting the engine component, locking the two inductors with respect to the common frame, moving the common frame away from the valve seats to provide the necessary coupling gap, and then energizing the inductors to inductively heat the valve seats preparatory to quench hardening thereof.

ilnited States Patent [191 Delpaggio METHOD AND APPARATUS FORINDUCTIVELY HEATING VALVE SEATS [75] Inventor: Anthony F. Delpaggio,Parma. Ohio [73] Assignee: Park-Ohio Industries, Inc.,

Cleveland, Ohio [22] Filed: June 9, 1971 [21] Appl. N0.: 151,493

[52] U.S. Cl 219/1057, 219/1043, 219/1071 [51] Int. Cl. .1 1105b 5/00[58] Field of Search 219/1057, 10.43,

[56] References Cited UNITED STATESPATENTS 2,797,289 6/1957 Georgen2l9/l0.57

Primary ExaminerJ. V. Truhe isii'sidm Examihf-l-high D. JaegerAttorney-Meyer, Tilberry and Body [5 7 ABSTRACT A method and apparatusfor simultaneously heating the conical surfaces of first and secondvalve seats lying generally in a given plane on an engine component,which method and apparatus comprises mounting two inductors forindependent reciprocal and lateral movemerit with respect to a commonframe and biased outwardly therefrom, moving the common frame toward theplane of the valve seats until each is stopped by contacting the enginecomponent, locking the two inductors with respect to the common frame,moving the common frame away from the valve seats to provide thenecessary coupling gap, and then energizing the inductors to inductivelyheat the valve seats preparatory to quench hardening thereof.

16 Claims, 14 Drawing Figures Patented July 3, 1973 7 Sheets-Sheet lINVENTOR- ANTHONY F. DEL PAGGIO BY Mega, 744m; 8 Bad;

ATTORNEYS Patentgd July 3, 1973 3,743,809

' 7 Sheets-Sheet 3 I ESOJ 252 INVENTOR. ANTHONY F. DEL PAGGIO BY I Memm, g Bad;

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INVENTOR. ANTHONY F. DEL PAGGIO 7M 8 Bad ATTORNEYS Patented July 3, 19737 Sheets-Sheet 5 Y INVENTOR.

J ANTHONY F. DEL PAGGIO 'T ORNEYS BY Maya, 7% 6? @049 Patented July 3,1973 7 Sheets-Sheet 6 FIG. ll

INVENTOR. ANTHONY F. DEL PAGGIO BY 44 WW, a Bad,

ATTORNEYS METHOD AND APPARATUS FOR INDUCTIVELY HEATING VALVE SEATS Thisinvention relates to the art of induction heating and more particularlyto a method and apparatus for inductively heating the valve seats of anengine component, such as an engine head.

The invention is particularly applicable for simultaneously heatingadjacent exhaust valve seats of a gray cast iron engine head, and itwill be described with reference thereto; however, it must beappreciated that the invention has broader applications and may be usedfor heating various types of valve seats in engine heads of variousmaterial and for heating similar types of work surfaces.

Internal combustion engines generally employ conical shaped valve seatswhich coact with reciprocal poppet valves for controlling flow of gasesto and from the cylinders. During operation of the engine, the exhaustvalves are subjected to extremely high temperatures and, thus,experience a substantial amount of wear. This wear was reduced bylubricants contained in gasoline, especially lead and phosphorous addedto the gasoline. Recently, gasolines are being used with reduced leadand/or phosphorous content; therefore, the exhaust valve seats aresubjected to more rapid deterioration. To counteract this, extensiveefforts have been devoted to increasing the physical properties of theexhaust valve seat during manufacturing.

It has been suggested to heat inductively the conical surface of theexhaust valve seats in an internal combustion engine by using a singleturn inductor positioned adjacent the valve seat, which inductorinductively heats the valve seat preparatory to quench hardening. Thistype of heating installation is extremely well adapted for automaticprocessing of the engine head, since the various exhaust valve seats inan engine head can be inductively heated in a single operation.Consequently, the efforts to improve the physical characteristics of theexhaust valve seats have generally been centered around a gang-typeinduction heating apparatus. These efforts have heretofore taken variouscourses. It is necessary to provide accurate and uniform magneticcoupling between the separate inductors and the conical surface of thevalve seats. To accomplish this, it has been suggested to bring thevarious inductors into position with respect to the valve seats and thenchange the magnetic coupling at each valve seat by a servo controlledmagnetically permeable core extending through the inductor. Also, it hasbeen suggested to shift the individual inductors with respect to thevalve seats in response to measured magnetic coupling characteristics.All of these efforts have met with limited success.

The present invention relates to a method and apparatus for accuratelypositioning the inductors with respect to the valve seats so that theinduction heating can be uniform without requiring servomechanisms andother individual controls on the separate inductors.

In accordance with the present invention, there is provided an apparatusfor positioning first and second generally circular inductors a common,preselected distance from first and second conical surfaces of a bodymember, which surfaces are to be inductively heated by the inductors.The conical surfaces lie generally in a common plane but may be slightlyoffset therefrom in a direction perpendicular tofthe plane. Thisapparatus comprises first and second carrier means for supporting eachof the first and second inductors, means for mounting the first andsecond carrier means onto a common frame for independent reciprocalmovement of the carrier means in a direction generally perpendicular tothe plane, means biasing each of the carrier means in a direction towardthe plane and with respect to the common frame, means for moving thecommon frame in a direction generally perpendicular to the plane andtoward the frame until after both of the common carrier means have beenstopped by the body member and have been moved independently of thecarrier frame, means for locking the first and second carrier means ontothe common frame, and means for moving the common frame in a directiongenerally perpendicular to the plane and away from the plane a selecteddistance corresponding to the preselected distance.

In this manner, the two inductors are biased outwardly from a commonframe and the common frame is moved into contact with the body memberwhich may be an internal combustion engine head. This then allows theseparate inductors to seek a common position with respect to the valveseats which they are to heat, preferably in contact with the seats. Thenall of the inductors are locked to the frame, and the frame is movedbackwardly a distance generally corresponding to the desired magneticcoupling distance for the separate inductors. Consequently, noservomechanisms are required, and relatively simple structures'areemployed to selectively control the spacing of the individual inductorsfrom their valve seats prior to heating.

In accordance with another aspect of the present invention, there isprovided a method including the steps of providing at least two singleturn inductors having shapes generally matching conical surfaces of thevalve seats, mounting both of these inductors for independent reciprocalmovement with respect to a common frame, biasing each of the inductorstoward the valve seats, moving the common frame toward the valve seatsuntil the engine head stops movement of the individual inductors, thenlocking the inductors onto the common frame, moving the common framebackwardly a preselected distance, and then energizing the inductors toinductively heat the individual valve seats.

In accordance with another aspect of the present invention there isprovided an induction heating device employing a cylindrical secondarywinding secured onto a movable inductor and movable therewith and arelatively fixed primary winding concentric with the secondary windingand having means for allowing both axial and radial movement between theprimary and secondary windings. By using this concept, slight movementof the inductor, which carries the secondary, can be accommodated in thegap between the primary and secondary windings. Consequently, theprimary winding may be fixedly mounted and without requiring flexibleleads 1 In accordance with another aspect of the present invention thereis provided an induction heating device.

for heating the conical surface of a valve seat of an engine headpreparatory to quench hardening wherein the engine head has a structuralelement fixed with respect to the center of the conical surface. Thisdevice comprises a support frame fixed in a direction radial of theconical surface, an inductor having a shape generally matching theconical surface and two input leads for energizing the inductor, acarrier means for supporting the inductor, means for mounting thecarrier means onto the support frame, which mounting means includesmeans for limiting movement of the carrier means to only a directionradial of the conical surface, and means on the carrier and adapted tocoact with the structural element of the head for shifting the inductorto a position with the inductor generally concentric with the conicalsurface.

This particular aspect of the present invention provides a floatinglocator on the inductor at each heating position. This floating locatoris capable of movement only transversely of the valve seat by a supportframe which has means for so limiting the movement of the locator. Inthis manner, if there is a slight misalignment of the inductor as it ismoving toward the valve seat, the locator contacts the engine head andshifts the inductor transversely or radially of the valve seat toprovide concentricity. This movement is relatively limited and can beaccommodated by the previously mentioned relative movement between thesecondary of the transformer, which is fixed to the inductor and theprimary of the transformer which is in a relatively stationary position.

The primary object of the present invention is the provision of a methodand apparatus for inductively heating the conical surface of a valveseat in an internal combustion engine, which method and apparatus isuniform in operation and relatively simple in structure.

FIG. is a cross-sectional view taken generally along line 10-10 of FIG.9;

FIG. 11 is a cross-sectional view taken generally along line 11-11 inFIG. 10;

FIG. 12 is an enlarged cross-sectional view taken generally along line12-12 of FIG. 1;

Another object of the present invention is the provision of a method andapparatus for inductively heating the conical surface of a valve seat inan internal combustion engine, which method and apparatus provideaccurate control of the magnetic coupling between the inductor and thevalve seat before the inductor is energized.

Still another object of the present invention is to provide a method andapparatus as defined above which do not employ servomotors or selectivecontrols for adjusting the magnetic coupling between the inductor andthe valve seat.

Still another object of the present invention is the provision of alocator device foran inductor to be used to heat inductively the conicalsurface of a valve seat, which device allows controlled movement of theinductor radial of the valve seat for the purposesof obtainingconcentricity.

Another object of the present invention is the provision of atransformer device for use in an induction heating installation whereinan inductor is moved with respect to the valve seat for the purposes ofobtaining concentricity, which transformer device employs a movablesecondary mounted directly onto the inductor and movable in a radialdirection with res'pect to a genj erally fixed primary concentric withsaidsecondary'. These and other objects and advantageswill becomeapparent from the following description taken together withtheaccompanying drawings in which:

FIG. 1 is a top plan view illustrating the preferred embodiment of thepresent invention;

FIG. 13 is a cross-sectional view taken generally along line 13-13 ofFIG. 12; and,

FIG. 14 is a graph illustrating schematically an operatingcharacteristic of the present invention.

Referring now to the drawings wherein the showings are for the purposeof illustrating a preferred embodiment of the invention only and not forthe purpose of limiting same, FIGS. 1 and 2 show an induction heatingdevice A and an engine head B held in position with respect to theapparatus byappropriate clamping device C, which form no part of thepresent invention. The engine head includes a plurality of spaced valveseats D generally lying in a common plane and within recessed exhaustports E. Concentric with the conical valve seats are a plurality ofbores F which are adapted to receive the valve stems of a normal poppetvalve. The apparatus A includes, as primary elements, an inductor,inductor carrier and inductor locator device 10, best shown in FIGS.8-11 and hereinafter also referred to as the inductor device; aninductor support and locking .device 12, best shown in FIGS. 13, 14; aninductor i transformer 14, best shown in FIGS. 3-8; a power input system16, best shown in FIGS. 1 and 2 and somewhat shown in FIGS. 3-7; asupport frame 20 for carrying the above mentioned mechanisms; avplatform 22 for reciprocally mounting support frame 20; a reciprocatingmechanism 24, schematically represented as a double acting cylinderfixed onto the platform 22 and connected to the support frame forreciprocating the support frame 'with respect to the platform; and,back-off mechanism 26.

GENERAL OPERATION inductor devices 10 has a biasing arrangement to allowFIG. 2 isa side elevational vlew taken generallyalong line 2-2 of FIG.1;

FIG. 3 is an enlarged cross-sectional view taken generally along line3-3 of FIG. I; 2

FIG. 4 is an end view taken generally along line 4-4 of FIG. 3;

FIG. 5 is a top view taken generally along line 5-5 of FIG. 3; I

FIG. 6 is a partial view taken generally along line 6-6 of FIG. 5;

the device to stop when the inductor thereof contacts the valve seat asthesupport frame 20 continues forward movement. After all. of theinductors are in the proper position with respect to the individualvalve seats, the locking device 12 looks all of the inductor devices 10in a fixed position with respect to the support frame 20. In thismanner, all variations in the spacing of 'the valve seats anddifferences in radial locations thereof are compensated for by themovement of the devices 10. After the locking has been effected, backoffmechanism 26 moves the support frame 20 backwardly a distancecorresponding to the desired coupling gap between the inductors and thevalve seats. In practice this back-off distance is less than 0.060inches and preferably in the general neighborhood of 0.045 inches whichprovides a gap of about 0.030 inches with the seat surface. After thisback-off movement, all of the inductors are in the proper heatingposition. Thereafter, the inductors are energized and the valve seatsare inductively heated for subsequent quenching by a vehicle ormechanism not forming a part of the present invention. It is alsocontemplated that the seats can be hardened by cooling caused by themass of the material which requires about 5-7 seconds. Thereafter, theinductors can be again energized at a lower power level for a shorttime, such as 3-5 seconds for quenching before the head is removed. Avariety of strictures could be utilized for accomplishing the abovementioned operation; however, in accordance with the preferredembodiment of the present invention certain specific structures arecontemplated. These structures will be hereinafter described in detail.

INDUCTOR, INDUCTOR CARRIER AND INDUCTOR LOCATOR DEVICE Referring nowmore particularly to FIGS. 8-11, one of the inductor, inductor carrierand inductor locator devices 10, referred to as the inductor devices, isshown in detail. A generally circular, single turn inductor 30 includesconnector leads 32, 34 electrically connected onto a hollow tube 36 anda hollow sleeve 38, respectively. Although the inductor is generallycircular, it can be somewhat elliptical to provide uniform heating. Thetube and sleeve are insulated by sleeves 40, 42. The basic connectorleads for the inductor 30 are, thus, the concentric tube 36 and thehollow sleeve 38. At one end of device there is provided an electricallyinsulated insert 50 which holds the inductor in place .and also supportsan outwardly extending tip 52 which includes a cylindrical shaft 54 thatis dimensioned to coact with bore F of the engine head B. Consequently,as device 10 moves forward, the shaft 54 registers with bore F andshifts the inductor 30 radially into a concentric relationship with thevalve seat D. This necessitates a mechanism for allowing movement of theinductor in a radial direction with respect to the valve seat; however,a tilting action must be minimized so that the magnetic coupling gapbetween the inductor and the valve seat will remain uniform around thetotal circumference of the valve seat. To accomplish this task, and inaccordance with the present invention, there is provided an arrangementwhich will allow the inductor to have slight transverse movement, but aminimum or no tilting action. I

In accordance with the preferred embodiment of the present invention, amechanism for accomplishing this translation function for the inductorincludes an inductor carrier-60 formed from an insulating material andsecured onto the hollow sleeve 38. The carrier includes an outwardlyextending flange 62 substantially parallel to the general plane of thevalve seat D. Bearing rings 64, 66 are positioned on oppositefacingsurfaces of flange 62 to coact with a support frame 70 in a manner to bedescribed.

Referring now to the support frame 70, this frame is mounted onto arearwardly extending sleeve 72 which is, in turn, mounted for onlyreciprocal movement in a mechanism to be described later. Consequently,frame 70 is restrained from movement in a radial direction with respectto the valve seat D. Frame 70 includes a back plate 74, a cylindricalspacer sleeve 76 and a front, or face, plate 80. A plurality ofcircumferentially spaced clamping bolts 82 are provided for drawing theface plate toward the back plate. A seal 84 which has sufficientresiliency to allow movement of the carrier 60 is provided between thecarrier and the face plate 80. Bearing rings 90, 92, similar to bearingrings 64, 66, are secured onto the back plate 74 and the face plate 80,respectively, to provide a bearing surface for ball cages 94, 96. Thesecages provide a series of rolling elements, such as balls, between thebearing ring. A plurality of rubber springs 98 are positioned betweenthe cages and the spacer sleeve 76 to maintain the cages centered. Acontrolled amount of pressure is applied to the balls of the cages 94,96 by the clamping bolts 82 so that movement of the'flange 62 can onlybe in a direction substantially parallel to the general plane of thevalve seat D.

Since it is advisable to center the carrier 60, and thus the inductor30, during each cycle of the apparatus A, there is provided a centeringmeans 110 which may take a variety of structural forms. In accordancewith the preferred embodiment of the present invention, the centeringmeans 110 includes a bore 112 in back plate 74 and adapted to receive acam block 114 having a stem 1l6 within the bore 112 and an outwardlyfacing head 118 having a conical recess 120. Flange 62 isprovided with abore 130 generally coinciding with the bore 112 in the back plate 74.Within this bore there is provided a sleeve 132. A ball 134 supported ona carrier 136 is reciprocally mounted on the sleeve 132, and isbiasedtoward the conical recess 120 by an appropriate spring 138. Thisarrangement assures that the carrier 60 is in a preselected positionbefore being shifted by the bore F. In practice, two of the centeringmeans 110 are provided on diametrically opposite portions of the device10. Since the conical recess 120 has a limited active distance a, thereis incorporated in the present embodiment an arrangement for limitingthe amount of radial shift that can be made by the carrier 60. Thelimiting arrangement is the radial spacing-b between flange 62 andspacer 76. Spacing b is no more than distance a which is the activedistance of the centering means 110. A gap 152 is provided betweensleeve 42 and sleeve 72. This gap has a dimension 0 which is slightlygreater than spacing b so that the sleeve 42 does not contact sleeve 72during normal operation of the device 10. To limit rotational movementof carrier 60, an element 140 includes a bore 142 within back plate 74and adapted to receive a pin 144 which'abuts retainer 146 and is held bya press fit. A

bore 150 within the flange 62 is dimensioned to provide a spacingbetween the pin 144 and the surface of the bore equal to spacing b. I

In summary, the inductor device 10 allows the inductor 30 to bepositioned concentrically with respect to the valve seat D without anytilting movement and without actually causing any movement of thesupport frame 70 which has an additional function which will bedescribed later and which is benefitted by the relative fixed positionof the support frame 70 during radial movement of the inductor 30 forthe purposes of concentricity.

INDUCTOR SUPPORT AND LOCKING DEVICE Referring now to FIGS. 12 and 13,the inductor support and locking device 12 provides for reciprocalmovement of the device supported on sleeve 72 and for locking inductordevice 10 in a reciprocal position determined by the backward movementof the inductor device 10 as it contacts the engine head during forwardmovement of the support frame 20. A variety of structures could be usedfor accomplishing this purpose; however, one structure is schematicallyillustrated and includes a frame 170 for supporting a housing 172.Within the housing there are two axially aligned bearings or bushings174, 176 which reciprocally support sleeve 72. A retainer 180 holdsbushing 174 in position. To prevent rotation of the sleeve 72, there isprovided a key 182 coacting with a keyway 184 in the sleeve. The keylimits movement of the sleeve 72 in both directions. In accordance withthe present invention, the inductor device 10 is biased forwardly towardthe block. In accordance with the illustrated embodiment of the presentinvention this is accomplished by a spring 190 surrounding the sleeve 72and creating a biasing action between bushing 176 and the back plate 74of support frame 70. By this structure, reciprocal movement is allowedand a biasing action is created.

To lock the sleeve 72 in a selected position with respect to housing172, there is provided a locking device 200 which includes a clamp ring202 surrounding the sleeve 72 and having aligned ears 204, 206. The ear206 coacts with a shoulder 208 during the locking operation. The lockingaction is effected by a cylinder 210 having a rod 212. Ring 202 has aridge 214 that coacts with annular recess 216 to center and limit theopening of the ring by its own resiliency.

In operation, when the rod 212 is in the position shown in FIG. 13, theclamp ring 202 is pulled down by a sleeve 220 and locks the sleeve 72with respect to housing 172. The operation of cylinder 210 shifts therod 212 to an upward position so sleeve 220 contacts the upper side ofthe housing. The resiliency of ring 202 opens the ring and releasessleeve 72 for reciprocal movement. The ring is centered by recess 216 toprevent drag on the sleeve 72.

Above the housing 172 there are provided two spaced switches 230, 232and actuators 234, 236 mounted onto the rod 212. These switches are usedto indicate whether the locking device is in the locked or unlockedposition. These switches are used in the electrical circuit for themachine which can take a variety of structural forms and is not a partof the present invention.

INDUCTOR TRANSFORMER AND RELATE v STRUCTURE I Referring now moreparticularly toI-IGS. 3-8, the inductor transformer 14 and its relatedstructure are illustrated. Basically, insulated bus bars 250, 252 aresupported by an appropriate support structure 352,

354, which does not form a part of the invention, and separated by aninsulation 256 are connected onto hollow, generally parallel inputstrips 260, 262. Coolant tubes 264, 266 are used to control thetemperature of the bus bars. Hollow input strips 260,262 are directedinto the actual transformer 270 which is best shown in FIGS. 6 and 7. Asingle sheet primary 272 is connected between the strips 260, 262 andincludes hollow conductors 274, 276. Within the primary winding 272there are provided a series of normal flux concentrators 280.Transformer 270 includes a secondary 290 in the form of a single sheet292 having an axially extending gap 294 and terminal ends 296, 298.There is a gap 299 between the primary sheet 272 and the secondary sheet292. This gap has a spacing d, shown in FIG. 7, which is at least asgreat as the spacing b between flange 62 and spacer 76. Consequently,any radial movement of the inductor device 10 is allowed by the gap 299.

In accordance with the illustrated embodiment of the invention, thesecondary 290 is cantilevered onto the inductor device 10 by beingcoupled directly onto and supported by the rearwardly extending tube 36and hollow sleeve 38. The connection between the tube and sleeve and thesecondary also forms the electrical connection to these elements forenergizing the inductor 30. A variety of structure could be used formaking this connection; however, in accordance with the illustratedembodiment of the present invention, end 298 of secondary 290 is coupledwith tube 36 by a coupling device 300 best shown in FIGS. 4, 5 and 8.This coupling device includes a block 302 welded onto end 298 and aclamping plate 304 for clamping tube 36 against the block 302. Withinthe block there is a bore 306 having a larger diameter than the diameterof the tube 36 and provided with spaced seals 310, 312 for the coolantsystem to be described later.

Secondary 290 is connected onto sleeve 38 at end 296 by a couplingdevice 320 best shownin FIGS. 5, 6 and 8. A block 322 is welded onto end296, and a clamp plate 324 clamps the hollow sleeve 38 with respect tothe block 322. Within the block there is provided a bore 326 having adiameter substantially greater than the diameter of the sleeve 38.Spaced seals 330, 332 are provided between the bore 326 and thesleeve'38 for a purpose to be described later.

In summary, the primary and secondary are both single sheets to providea 1:1 ratio. This transformer is primarily utilized for providing arelatively fixed primary and a movable secondary which can be carried bythe inductor itself and can move with respect to the primary asdescribed. This allows for radial adjustment of the inductor withrespect to the valve seat without requiringmovement of the primary.

During forward movement of device 10, an arm 340 bolted onto the back ofblock 302 contacts-an adjustable switch head 342 which contacts springbiased switch head 344 to indicate forward movement of carrier 22.

POWER SYSTEM Although the power system does not form a part of thepresent invention, it will be describedprimarily in connection withFIGS. land. 2. A normal step-down transformer 350 is supported by andfastened onto frame 20. Output leads 360, 362 are separated by aninsulation member 364 and are connected in series. with bus bar sections370, 250, 252, 372, and 374 which connect the inductor transformers 14at positions 1, II, III, and IV in series. The particular bus bararrangement described in connection with the inductor transformer is thearrangement particularly used at position II; however, the remainingconnections are essentially the same and are clearly evident from FIG.1.

TRANSFORMER COOLANT SYSTEM A variety of arrangements could be providedfor cooling the transformer 270; however, in accordance with theillustrated embodiment of the present invention, the primary of thetransformer is cooled by a coolant entering through an inlet 380 whichdirects the coolant through the hollow strip 262 into a pair of passages382 extending through conductors 274, 276. From these passages, acoolant enters passage 384 of hollow strap 260 and then exits from anoutlet 386. The secondary is cooled in a similar manner. Coolant entersthrough an inlet 390 and then flows around a circumferentially extendinghollow conductor 392 to a hollow cross-over conductor 394. From there,the coolant again flows around the secondary sheet 292 in a hollowconductor 396 which directs the coolant to an outlet 398.

INDUCTOR COOLANT SYSTEM In accordance with the present invention, thereis provided a system for cooling the inductor 30. This system, which isbest illustrated in FIGS. 8 and 10, includes an inlet 400 for directinga coolant into a cavity 402 where it is communicated with bore 306 andthen to ports 404 within tube 36. The coolant then flows through passage406 within the tube 36 to lead 32, through this lead, through inductor30, through lead 34 and then to port 410 in the hollow sleeve 38.Coolant then flows through the annular passage 412 to ports 414 whichare in communication with a cavity 416. From the cavity 416, the coolantexits through an outlet 418.

FEEDING AND BACK-OFF MECHANISMS As previously mentioned, cylinder 24moves frame 20 forward to set the inductor devices with the inductors 30in contact with the respective valve seats F. Thereafter the back-offmechanism 26 is actuated. This mechanism may take various structuralembodiments; however, the illustrated embodiment includes a supportslide 420 for supporting the cylinder 24 and reciprocated on surface422. A pinion 424 is geared to the slide 420 and is rotated by a rack426 operated by a cylinder 428. A stop 430 is used to limit movement ofrack 426 and is adjustable with respect to block 432 by a bolt head 434.Consequently, when the frame 20 is being moved by cylinder 24 slide 420is against a shoulder 440. After the inductor devices have been movedback and locked, cylinder 428 actuates rack 426 to shift slide 420 andcylinder 24 backwardly a distance controlled by stop 430. The inductorsare now spaced from the valve seats for heating.

OPERATION OF THE METHOD AND APPARATUS The operation of the method andapparatus has been disclosed in connection with the separate individualstructures employed; therefore, only a recapitulation of the generalmethod and apparatus is required. An engine head B is positioned asshown in FIGS. 1 and 2 and the locking devices 200 are released so thatthe inductor locator and support devices are all biased outwardly bytheir springs 190. The outward movement is controlled by the key 182 ateach station. Cylinder 24 then moves to the frame a distanceapproximately 3 inches at which time tip 52 registers with bore F whichshifts the carrier 60 within frame 70 in a lateral direction only tobring the inductor 30 into concentricity with the valve seat D at eachstation. Continued movement of the frame 20 brings the individualinductors 30 into contact with their respective valve seats. At thattime, the frame 20 continues movement and devices 10 remain stationary.This changes the relative position of the devices 10 with respect to thesupport and locking device 12. After sufficient movement has been madeto locate each of the inductors with respect to their valve seats, theforward movement of the frame is stopped. Then the cylinders 210 areactuated to clamp sleeve 72 with respect to frame by ring 202. Thiscompensates for any variation in the relative spacing between therespective valve seats. Cylinder 428 then moves the frame 20 away fromthe valve seats a distance corresponding to the desired gap between thevalve seats and the inductors 30. Thereafter, frame 20 is stopped andthe heating cycle is commenced. During lateral adjustment of therespective inductors, the secondary 290 moves within the primary 272without contacting the same. This general operation cycle is illustratedin FIG. 15.

In practice the inductors are powered by an oscillator having afrequency between 290-450 Kc and each inductor is energized with about10-12 kilowatts for about 6-9 seconds. The inductors are de-energizedfor about 5-7 seconds which allows the mass around the seat to cool theseat and cause hardening. Then, the inductors are again energized by thesame oscillator at a power of about 5 kilowatts for about 3-5 secondsfor tempering. This reduces stresses in the surfaces of the valve seats.

Having thus defined my invention, I claim:

1. A method of inductively heating the conical surface of a valve seatcoaxially aligned with a bore in an engine component, said methodcomprising the following steps:

a. providing a single turn inductor having a shape generally matchingsaid surface;

b. mounting said inductor for reciprocal movement with respect to aframe and in a direction generally parallel to the axis of said bore;

c. biasing said inductor in a direction toward said engine component;

(1. moving said frame toward said engine component with said inductorgenerally aligned with said valve seat; 7

e. stopping the movement of said inductor at apreselected location whilesaid frame continues to move toward said engine component;

f. thereafter stopping the movement of said frame toward said enginecomponent;

g. then, locking said inductor with respect to said frame;

h. moving said frame and inductor away from said engine component aselected distance to provide proper spacing of said inductor from saidsurface; and,

i. energizing said inductor to thereby inductively heat said surface.

2. A method as defined in claim 1 wherein said selected distance isbetween about 0.015 0.050 inches.

.3. A method as defined in claim 1 wherein said selected distance isapproximately 0.040 inches.

4. A method as defined in claim 1 including the step j. aligning saidinductor in an axial direction with said valve seat as said frame ismoving toward said engine component.

5. An induction heating device for heating the conical surface of avalve seat of an engine component preparatory to quench hardening, saidengine component having a structural element fixed with respect to thecenter of said conical surface, said device comprising: a support framefixed in a direction radial of said conical surface; an inductor havinga shape generally matching said conical surface and two input leads forsaid inductor; means for mounting said carrier means onto said supportframe, said mounting means including means for limiting movement of saidcarrier means to only a direction radially of said conical surface; and,

means on said carrier and adapted to coact with said structural elementof said component for shifting to, and holding'said carrier in, aposition with said inductor generally concentric with said surface. v

6. An induction heating device as defined in claim including a firstlocator means on said frame and a second locator means on saidcarrier,said first and second locator means coacting to bias said carrier, andthus said inductor, into a preselected position with respect to saidframe. I

7. An induction heating device as defined in claim 6 wherein one of saidlocator means isa cam member and the other of said locator means is afollower member and means for baising said members together in adirection generally axial of said conical surface.

8. An induction heating device as defined in claim 5 wherein saidmounting means includes a flange on said carrier means, said flangelying in a plane generally perpendicular to the axis of said'conicalsurface and said limiting means includes clamping means actingperpendicularly against said flange.

9. An induction heating device as defined in claim 8 wherein saidclamping means includes a series of roller elements in contact with saidflange and means for forcing said roller elements against said flange ina direction generally parallel to the axis of said conical surenergizingsaid-inductor; a carrier means for supporting face.

10. An induction heating device as defined in claim 8 including a firstlocator meanson said frame and a second locator means on said flange,said first and second locator means coacting to bias said flange, andthus said inductor, into a preselected position with respect to saidframe. I I r I 11. An induction heating device as defined in claim 5wherein said leads extend in a direction away from said conical surface,and including 7 a transformer spaced from said frame, said transformerincluding a relatively fixed primary having a central opening with anaxis generallyparallel to the axis; of said conical surfaceandasecondary within isaid opening, fixed onto said leads and movablewith respect to said primary in a direction generally radialiof said.conicalsurface.

12. An induction heating device as defined in claim 11 including meansfor shifting said frame with respect to said fixed-primary in adirection generally parallel to the axis of said conical surface andmeans for allowing said secondary to move within said opening in adirection generally parallel to said axis of said conical surface.

13. An induction. heating device as defined in claim 12 including meansfor locking said frame with respect to said fixed primary duringenergization of said inductor.

14. An induction heating device as defined. in claim 13 including meansfor selectively moving, in unison, said primary and said frame between afirst position with said inductor spaced from said conical surface and asecond position with said inductor adjacent said conical surface.

15. An induction heating device as defined in claim 5 including guidemeans for mounting said frame for reciprocal movement in a directiongenerally parallel to the axis of said conical surface.

16. An inductionheating device as defined in claim 15 including meansfor selectively locking said frame with respect to said guide means.

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1. A method of inductively heating the conical surface of a valve seatcoaxially aligned with a bore in an engine component, said methodcomprising the following steps: a. providing a single turn inductorhaving a shape generally matching said surface; b. mounting saidinductor for reciprocal movement with respect to a frame and in adirection generally parallel to the axis of said bore; c. biasing saidinductor in a direction toward said engine component; d. moving saidframe toward said engine component with said inductor generally alignedwith said valve seat; e. stopping the movement of said inductor at apreselected location while said frame continues to move toward saidengine component; f. thereafter stopping the movement of said frametoward said engine component; g. then, locking said inductor withrespect to said frame; h. moving said frame and inductor away from saidengine component a selected distance to provide proper spacing of saidinductor from said surface; and, i. energizing said inductor to therebyinductively heat said surface.
 2. A method as defined in claim 1 whereinsaid selected distance is between about 0.015 - 0.050 inches.
 3. Amethod as defined in claim 1 wherein said selected distance isapproximately 0.040 inches.
 4. A method as defined in claim 1 includingthe step of: j. aligning said inductor in an axial direction with saidvalve seat as said frame is moving toward said engine component.
 5. Aninduction heating device for heating the conical surface of a valve seatof an engine component preparatory to quench hardening, said enginecomponent having a structural element fixed with respect to the centerof said conical surface, said device comprising: a support frame fixedin a direction radial of said conical surface; an inductor having ashape generally matching said conical surface and two input leads forenergizing said inductor; a carrier means for supporting said inductor;means for mounting said carrier means onto said support frame, saidmounting means including means for limiting movement of said carriermeans to only a direction radially of said conical surface; and, meanson said carrier and adapted to coact with said structural element ofsaid component for shifting to, and holding said carrier in, a positionwith said inductor generally concentric with said surface.
 6. Aninduction heating device as defined in claim 5 including a first locatormeans on said frame and a second locator means on said carrier, saidfirst and second locator means coacting to bias said carrier, and thussaid inductor, into a preselected position with reSpect to said frame.7. An induction heating device as defined in claim 6 wherein one of saidlocator means is a cam member and the other of said locator means is afollower member and means for biasing said members together in adirection generally axial of said conical surface.
 8. An inductionheating device as defined in claim 5 wherein said mounting meansincludes a flange on said carrier means, said flange lying in a planegenerally perpendicular to the axis of said conical surface and saidlimiting means includes clamping means acting perpendicularly againstsaid flange.
 9. An induction heating device as defined in claim 8wherein said clamping means includes a series of roller elements incontact with said flange and means for forcing said roller elementsagainst said flange in a direction generally parallel to the axis ofsaid conical surface.
 10. An induction heating device as defined inclaim 8 including a first locator means on said frame and a secondlocator means on said flange, said first and second locator meanscoacting to bias said flange, and thus said inductor, into a preselectedposition with respect to said frame.
 11. An induction heating device asdefined in claim 5 wherein said leads extend in a direction away fromsaid conical surface, and including a transformer spaced from saidframe, said transformer including a relatively fixed primary having acentral opening with an axis generally parallel to the axis of saidconical surface and a secondary within said opening, fixed onto saidleads and movable with respect to said primary in a direction generallyradial of said conical surface.
 12. An induction heating device asdefined in claim 11 including means for shifting said frame with respectto said fixed primary in a direction generally parallel to the axis ofsaid conical surface and means for allowing said secondary to movewithin said opening in a direction generally parallel to said axis ofsaid conical surface.
 13. An induction heating device as defined inclaim 12 including means for locking said frame with respect to saidfixed primary during energization of said inductor.
 14. An inductionheating device as defined in claim 13 including means for selectivelymoving, in unison, said primary and said frame between a first positionwith said inductor spaced from said conical surface and a secondposition with said inductor adjacent said conical surface.
 15. Aninduction heating device as defined in claim 5 including guide means formounting said frame for reciprocal movement in a direction generallyparallel to the axis of said conical surface.
 16. An induction heatingdevice as defined in claim 15 including means for selectively lockingsaid frame with respect to said guide means.